Ignition distributor



March 29, 1949.

H. R. GRANT IGNITION DISTRIBUTOR Filed Jan. 16, 1947 B. Grani- INVENTOR.

4770mm? Y Patented Mar. 29, 1949 UNITED STATES PATENT OFFICE IGNITION DISTRIBUTOR Harold R. Grant, Detroit, Mich., assignor to George M. Holley and Earl Holley Application January 16, 1947, Serial No. 722,303

1 Claim.

The object of this invention is to improve the mechanism for advancing the spark on an automobile engine.

A vacuum operated diaphragm is used to advance the spark as the speed increases and as the inlet manifold pressure falls. As the vacuum available is very small even at high speed the diaphragm has to be large enough to overcome the friction of th mechanism. Hence, it is important that the mechanism ofier the least possible resistance to the spark advance. Furthermore, friction introduces hysteresis and therefore when the spark is being advanced with increasing speed the characteristic is diflerent to when the speed is being reduced with the throttle wide open.

Fig. 1 shows a plane view of the circuit breaker together with a diagrammatic illustration of the air inlet.

Fig. 2 shows a cross sectional elevation of the bearing which eliminates a greater portion of the friction.

In Figs. 1 and 2, In is the drive shaft carrying a cam l2. The suction operated diaphragm l4 responds to the suction in the venturi l6 when the throttl I8 is wide open and to the suction below the throttle i8 when the throttle I8 is first opened away from the idling position in which it is shown. Diaphragm I4 is connected through a rod 20 to a plate 22.

The advance of the ignition is resisted by two springs 24 and 26. The springs are carried on the plate 22 by pins 28 and 30, and are anchored to the base through the pins 40 and 42. The usual circuit breaker arm 82 is carried and the usual electrical connections are provided.

The feature of this invention is in the porous bushing 34 which acts as a bearing for the shaft I and also as a bearing for the plate 22. Plate v22 is thus held concentric with the shaft in.

An annular groove 46 in the bearing 34 is supplied with oil through a wick 38.

Operation In the operation of this ignition device when the throttle I8 is wide open the suction in the 2 venturi I6 is comparatively weak. This weak force when applied to the diaphragm I4 first stretches the spring 24 and then brings the spring 26 into action. Spring 26 is arranged, as shown, to be loose on the pin 40 whereas the spring 24 is tight on the pin 42. The pins 40 and 42 are stationary pins and the pins 28 and 30 are movable pins carried by the plate 22.

. Although the force acting on the diaphragm I4 is relatively feeble the porous bushing 34 provides lubrication for the plate 22 and thus permits the desired advance.

What I claim is:

A spark advance mechanism for an internal combustion engine having a casing with a porous bushing mountedtherein and projecting therefrom, a drive shaft driven at one-half ngine speed, a cam mounted on said shaft, a rotatable circuit breaker plate carrying circuit breaker mechanism having a bearing, a bearing surface on the inside of said porous bushing which acts as a bearing for said shaft, a bearing surface on the outside of the projecting portion of said bushing which engages with the bearing of the circuit breaker plate to positively hold th plate concentric with said cam, an annular chamber between the casing and the bushing acting as an oil reservoir for both bearings.

HAROLD R. GRANT.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,415,370 Lehman May 9, 1922 1,873,146 Patch Aug. 23, 1932 1,947,400 Allendorff Feb. 13, 1934 2,131,019 Arthur et al. Sept. 27, 1938 2,202,077 Arthur May 28, 1940 2,406,891 Newton et al. Sept. 3, 1946 FOREIGN PATENTS Number Country Date I 463,463 Great Britain Mar. 31, 1947 

